1. Field of the Invention
The present invention relates to the technology field of power electronic circuits, and more particularly to a novel wind power charging circuit with three-phase, single-stage and bridgeless framework.
2. Description of the Prior Art
In order to facilitate environment be sustainable developed, government by country has made great efforts to develop the use of green energies, so as to carry out the diversification of energy use. In all of the green energies, solar power and wind power are the most developmental.
When a wind turbine system works for generating electricity, a plurality of blades of a wind turbine of the wind turbine system rotate to produce mechanical energy by the driving of wind power, and the produced mechanical energy subsequently drive a plurality of rotors of a generator of the wind turbine system. The electric power generated by the wind turbine system must be treated with a power conversion process by using a particularly-designed power converting device before being outputted to an electricity bank or a load.
Please refer to FIG. 1, which illustrates a framework view of a conventional wind turbine system. Because the input voltage and current of the power converting device 11′ corresponding to the maximum power point of the wind turbine G′ change with different wind speeds, the power converting device 11′ must consists of a three-phase power factor correction (PFC) unit 111′ and a power converting unit 112′ in order to enhance the electromechanical conversion efficiency of the wind turbine system 1′ shown by FIG. 1. In which, the three-phase PFC unit 111′ is used for making the phase of three phase currents outputted by the wind turbine G′ be equal to the phase of three phase voltages, so as to achieve a higher power factor. On the other hand, the power converting unit 112′ is used to make the wind turbine G′ be operated at the maximum power point under different wind speeds.
However, inventors of the present invention find that, because the three-phase PFC unit 111′ includes EMI filter or diode rectifier, the conventional wind turbine system 1′ shows the shortcoming of poor input efficiency under low voltage and high current operation. In addition, when the diode rectifier is replaced by a capacitor rectifier, the wind turbine system 1′ reveals the drawbacks of distortion of input current and vibration of wind turbine. Although researchers propose that the input current distortion can be solved by replacing the three-phase PFC unit 111′ with a bridgeless PFC unit, the wind turbine system 1′ still includes the disadvantages of huge framework and high assembly cost because the wind turbine system 1′ is constituted by two stage circuit units.
Accordingly, in view of the power converting device used in the conventional wind turbine system 1′ includes many shortcomings and drawbacks, the inventor of the present application has made great efforts to make inventive research thereon and eventually provided a novel wind power charging circuit with three-phase, single-stage and bridgeless framework.